Priming layers are used when bonding or coating two different materials together. One objective of the priming layer is to control the level of adherence of one material to another. The priming layer can be used to increase bond strength between two layers.
Where a coating is applied to a substrate and the composition of the coating does not have a natural affinity for the substrate, a primer layer can be used. Materials such as polyethylene terephthalate or polyolefins have well known problems in having coatings adhered thereto.
As adhesives are being designed with higher and higher adhesion to adherends and or target surfaces, the need for better and better priming is recognized to provide the required bond strength between the backing and the adhesive of these adhesive articles. The ability to provide higher strength primers or tie layers on specific target backings enables the creation of new adhesive articles having aggressive adhesives.
A number of coatings that utilize metal oxide particles have been prepared. In some the coatings are anti-reflective (AR) coatings. PCT Publication No. WO 96/18691 (Scholz et al.) describes coating compositions that impart anti-reflective and anti-fog properties to substrates coated therewith. The coating composition utilizes an inorganic metal oxide in combination with particular anionic surfactants. In US Patent Publication No. 2014/0022644 (Hao et al.) antireflective films are described comprising a light transmissive substrate and a low refractive index layer disposed on the light transmissive substrate. The low refractive index layer comprises the reaction product of polymerizable resin composition comprising at least 20 wt-% fumed silica.
Application U.S. Patent Ser. No. 62/055,758 filed Sep. 26, 2014, describes aqueous coating compositions for floor finishes or polishes that include modified particles that have an inorganic core and a surface that includes hydrophobic and hydrophilic moieties adhering to the surface.
In US Patent Publication No. 2012/0282455 (Hao et al.), nano-porous adhesive tie layers are described that include a binder including a multifunctional acrylate and a polyurethane, surface treated nanoparticles dispersed in the binder, and a plurality of interconnected voids.